Bathtub



FIG. 1 is a top perspective view of a bathtub showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a cross sectional view taken on line III--III of FIG. 2; and

FIG. 4 is a cross sectional view taken on line IV--IV of FIG. 2. 

The ornamental design for a bathtub, as shown and described. 